1. Field of the Invention
The invention relates to a method and arrangement for embedding supplemental data in a digital video signal. The invention also relates to an arrangement for decoding the embedded supplemental data.
2. Description of the Related Art
Video and audio signals are increasingly transmitted and recorded in a digitally encoded form, for example, an MPEG bit stream. There is a growing need to accommodate supplemental data in the signal, for example, a watermark to classify the signal as authentic program material. Watermarking digital signals is particularly useful in copy protection applications. The watermark can effectively take the form of a single bit indicating that the signal constitutes copy protected material, or a multi-bit code representing the originator of the material.
In the known MPEG standard for audio and video compression, a copy protection bit has been defined for that purpose. However, a disadvantage of this known method is that the protection bit can easily be modified to circumvent the copyright protection mechanism.